Abstract: The characteristics of the tropical and extra-tropical atmospheric low frequency oscillation during the summer of 1998 is studied based on the ECMWF grid wind and height data. Results show that intraseasonal oscillation over Asian monsoon regime is obvious. Latitudinal propagation of zonal wind at 850 hPa intraseasonal oscillation show that oscillation of westerlies over the South China Sea region is affected by two separated branches of northern and southern westely belts. Atmospheric circulation systems (Ural blocking high pressure and western Pacific subtropical high pressure) which are closely associated with severe flood around Changjiang River basin strongly response to intraseasonal oscillation. Persistent anomalies are active over the Eurasian continent. Activities of atmospheric low frequency wave are closely associated with the forming of circulation perisistent anomalies. Intraseasonal oscillation is the key to simultaneous occurrence of persistent anomalies at high and low latitudes. Distribution of low frequency (30～60 d) teleconnection pattern is an analogue to the wave train structure of Changjiang and Huaihe River flooding year are analogue.